1. Field of the Invention
The present invention relates generally to the structure and use of medical catheters. More particularly, the present invention relates to the construction and use of an infusion or delivery catheter designed to selectively deliver fluid radially or axially into an anatomical lumen.
Delivery catheters are used for a variety of surgical applications, such as infusing therapeutic fluids into a desired location within a patient's vasculature. To position the delivery catheter into the target site, a guide wire is typically introduced percutaneously or through an open surgical incision and advanced to the target location within a fluid vessel. The delivery catheter is then introduced over the guide wire until the distal end of the catheter or a fluid delivering portion of the catheter reaches the target site. After reaching the target site, the therapeutic fluid is delivered through an axial lumen in the catheter and onto the target site through openings in the catheter body.
In many applications, it is often desirable to deliver the therapeutic fluid radially outward from the catheter directly onto the target site within the body lumen. For example, thrombolytic agents are often delivered onto a restriction or lesion in a blood vessel caused by a thrombosis or clot to lysis the clot and restore blood flow in the lumen. To accomplish this, lateral infusion ports are typically formed near the distal end of the catheter body for allowing fluid to flow radially outward from the axial lumen through the infusion ports to the surrounding blood vessel. Delivering the thrombolytic agents directly to the thrombosis results in faster lysis of the clot and restored blood flow in a shorter amount of time.
The need to radially deliver fluid through lateral infusion ports is problematic in delivery catheters intended for introduction into small body lumens over guide wires. Existing catheters typically have distal guide wire ports in communication with the axial lumen of the catheter body for allowing the catheter to be advanced over the guide wire. Unfortunately, the momentum of the fluid flowing through the axial lumen and the relatively small size of the radially disposed infusion ports often causes a substantial portion of the fluid to flow past these infusion ports, where it is discharged axially through the guide wire port. In addition, the restriction or lesion in the blood vessel may often cover or partially restrict flow through the infusion ports, which increases the difficulty of delivering fluid through these radially disposed ports. The fluid delivered through the guide wire port is typically wasted downstream of the blockage, which may increase the time required to treat the lesion and restore the blood flow through the vessel.
For these and other reasons, it would be desirable to provide improved catheters and methods for infusing fluids onto target sites within anatomical lumens. These catheters and methods should be capable of delivering fluid flow radially outward through infusion ports directly onto, for example, a restriction or lesion in a blood vessel. In particular, these catheters should be capable of delivering the fluid through the infusion ports when the lesion partially covers or otherwise inhibits fluid flow through these ports.
2. Description of the Background Art
U.S. Pat. No. 4,661,094 describes a perfusion catheter having an inner tube which receives a guide wire for advancing the catheter through a body lumen. The catheter has a plurality of longitudinally spaced holes for permitting the flow of liquid from and into the flow passage through the holes when the catheter is positioned in a lesion or restriction within the body lumen. U.S. Pat. No. 5,334,154 describes a balloon angioplasty catheter having lateral perfusion ports in the catheter body. The perfusion ports have inwardly depressed proximal edges for preventing the excursion of a guide wire inserted into the catheter through the perfusion ports. U.S. Pat. No. 5,318,529 describes an angioplasty balloon catheter having a guide wire tube which receives a guide wire permanently received in an inflation lumen of the catheter. The guide tube has a very close tolerance over the guide wire, preferably below 0.0005 inch, and is optionally filled with a thixotropic material or elastomeric seal to prevent blood seepage and loss of inflation medium. Other drug infusion catheters having lateral ports include U.S. Pat. Nos. 5,209,728, 5,021,044, 4,543,087 and 5,300,022 and PCT application No. WO 094/08653.
A balloon catheter having a single lumen for both inflation and receiving a guide wire is described in co-pending application Ser. No. 08/415,002, filed on Mar. 31, 1995, naming William Tremulis as inventor. The full disclosure of the co-pending application is incorporated herein by reference. Other patents disclosing balloon catheters having guide wire and inflation lumens in different combinations include U.S. Pat. Nos. 4,413,989, 5,380,282, 5,378,237, 5,364,347, 5,330,428, 5,312,340, 5,246,420 and 5,201,754.